1. Field of the Invention
The present invention relates to a document reading apparatus for optically reading images on documents such as vouchers and forms, and more particularly to a document reading apparatus used in banking business that performs optical character recognition (OCR) on public money vouchers and payment/receipt slips and reads images on a variety of documents to input diagrammatic and line-drawn images.
2. Description of Related Art
Among document reading apparatuses designed to take in images on documents, including images of various kinds of vouchers and slips to be OCR-processed and images of seals, portraits and signatures on documents, there are mainly two types. One is a fixed sensor type in which an image sensor (line sensor) for optically reading a one-dimensional image is held immovable and a document is fed over the image sensor to read an image. Another is a flat bed scanner type in which a sensor is moved relative to a document placed on a bed to read an image.
In recent years a document reading apparatus has been proposed which employs a camera incorporating a two-dimensional image reading sensor (referred to as a two-dimensional sensor type). A scanner of the two-dimensional sensor type has a small number of two-dimensional sensor pixels and thus at present has difficulty in reading images at a resolution high enough to be able to optically recognize characters on a document. Therefore, the scanner is applied to reading only a narrow area of an image. To improve this type of the document reading apparatus, it may be possible to arrange a head section including a lens over the face of the document and move a one-dimensional image reading head or sensor in a sub-scan direction on a plane where the image of the document is focused through the lens (referred to as a main-/sub-scan type).
The document reading apparatuses of the two-dimensional sensor type and the main-/sub-scan type can read images even in those cases which cannot be dealt with by the document feeding type, i.e., in cases where a job involves the use of different kinds of documents having different sheet thicknesses or where a plurality of sheets are bound. These types of the document reading apparatuses can also prevent the face of a document to be scanned from being hidden from a user as it is in the flat bed scanner type.
Among literatures that describe technologies related to these document reading apparatuses is JP-A-5-153344.
The above-described types of the document reading apparatuses have a drawback of increased size because the document is fed or it is placed on a bed. The two-dimensional sensor type and the main-/sub-scan type, too, have a drawback in addition to an increased size. That is, the read head section, because it protrudes over the document face, can become an obstacle to an operator putting the document in place or pose a safety problem that the operator may hit against it.
An object of the present invention is to provide a document reading apparatus which allows easy setting of a document to be read and has good operability.
Another object of the present invention is to provide a document reading apparatus which directly drives an image reading sensor which can read a variety of kinds of documents.
In concrete terms, it is the object of the present invention to provide a document reading apparatus which is improved over the two-dimensional sensor type and main-/sub-scan type of document reading apparatuses suited for reading documents used in banks; which has improved operability and safety in putting a document in place; and which has an improved shape, compared with the conventional apparatus in which the head section protrudes over the face of the document impairing the appearance of the apparatus as well as the office.
To achieve these objectives, the present invention comprises: a reading sensor arranged deviated from the center of a document to be read and adapted to be moved when reading an image of the document; a drive circuit for driving the reading sensor; a correction device for correcting a result of reading performed by the reading sensor; and a display for displaying the image corrected by the correction device.
The document reading apparatus of the invention has an image reading section that includes an optical system, in which an extended line of an image plane of the document, an extended line of a lens perpendicular to the lens optical axis, and an extended line of a light receiving plane of the image sensor are intersected at one point.